What is a digital signature?

A digital signature is a specific type of electronic signature that employs cryptographic techniques to ensure the integrity and authenticity of a document. This means that when a document is digitally signed, it provides a method for verifying that the signer is indeed who they say they are and that the document has not been altered in any way after it was signed.

Digital signatures use algorithms and encryption to create a unique digital code that is attached to the document, making it virtually impossible to forge or tamper without detection. This is particularly important in legal and financial contexts, where the authenticity of documents must be guaranteed.

Other choices do not represent digital signatures accurately. For example, an official seal used for notarizing documents refers to a physical method of validation distinct from digital processes. A physical signature written on paper does not involve any electronic components or cryptographic protection. An index of legal documents is merely a reference list and does not involve the act of signing or verifying the content of a document. Thus, the correct choice highlights the unique characteristics and security features that define a digital signature.